Device Interface SDK

The Device Interface SDK package is for advanced users desiring to develop their own custom software applications for communicating with Garmin GPS products.
The Serial Protocol is based on RS-232. The voltage characteristics are compatible with most hosts; however, the device transmits positive voltages only, whereas the RS-232 standard requires both positive and negative voltages.
Also, the voltage swing between mark and space may not be large enough to meet the strict requirements of the RS-232 standard. Still, the device voltage characteristics are compatible with most hosts as long as the interface cable is wired correctly.
The other electrical characteristics are full duplex, serial data, 9600 baud, 8 data bits, no parity bits, and 1 stop bit. The mechanical characteristics vary among devices; most devices have custom-designed interface connectors in order to meet Garmin packaging requirements. The electrical and mechanical connections to standard DB-9 or DB-25 connectors can be accomplished with special cables that are available from Garmin.
Applications send packets to the device using the Win32 WriteFile function. If the packet size is an exact multiple of the USB packet size, an additional call to WriteFile should be made passing in no data.
Applications receive packets asynchronously from the device by constantly calling the Win32 DeviceIoControl function. When an application receives a Data Available packet, it should read packets using the Win32 ReadFile function. Once an application begins receiving packets for a protocol using DeviceIoControl or ReadFile, all subsequent packets for that protocol will be received using the same function.System requirementsVisual Studio